The present invention is directed to a low sulfur, low sulfated ash and low phosphorus lubricating oil composition for low emission heavy duty diesel engines comprising (a) a major amount of an oil of lubricating viscosity and (b) a detergent composition comprising a (i) a mixture of a metal salt of an alkyl hydroxyaromatic carboxylic acid and a metal salt of an alkyl phenol, and (ii) a metal salt of a Mannich condensation product of an alkyl phenol. The present invention is also directed to a low sulfur, low sulfated ash and low phosphorus lubricating oil concentrate comprising (a) an oil of lubricating viscosity and (b) a detergent composition comprising a (i) a mixture of a metal salt of an alkyl hydroxyaromatic carboxylic acid and a metal salt of an alkyl phenol, and (ii) a metal salt of a Mannich condensation product of an alkyl phenol.